Tweak fullscreen texture shaders

shader/texture/boxBlur.frag

@@ -0,0 +1,34 @@
+#version 430 core
+in vec2 vTexPos;
+out vec4 fColor;
+
+uniform vec2 winSize;
+uniform sampler2D screenTexture;
+
+const float hOff = 2.0 / 600;
+const float vOff = 2.0 / 600;
+const float frac = 1.0 / 9;
+const vec2 off[9] = vec2[](
+      vec2( vOff,hOff )
+    , vec2( vOff,0.0 )
+    , vec2( vOff,-hOff )
+    , vec2( 0.0,hOff )
+    , vec2( 0.0,0.0 )
+    , vec2( 0.0,-hOff )
+    , vec2( -vOff,hOff )
+    , vec2( -vOff,0.0 )
+    , vec2( -vOff,-hOff )
+    );
+
+void main()
+{
+    vec4 sampleTex[9];
+    for(int i=0; i<9; i++)
+    {
+        sampleTex[i] = vec4(texture(screenTexture, vTexPos + off[i]));
+    }
+    vec4 col = vec4(0,0,0,0);
+    for (int i = 0; i < 9; i++)
+        col += sampleTex[i] * frac;
+    fColor = col;
+}